A Novel and Convenient Route to Phosphono-Oligopeptides Derived from 1,3-Oxazolines, 1,3-Oxazines and 1,3-Thiazolines

Still Relevant Today: The Asinger Multicomponent Reaction

The Asinger multicomponent reaction is a versatile synthetic tool which gives access to multiple drug-like scaffolds such as 3-thiazolines. The diversity and easy access of its starting materials, its operational simplicity combined with mild conditions and relatively good yields, renders the Asinger reaction, today more than ever, a cornerstone not only in heterocyclic chemistry and modern synthesis but also in medicinal chemistry. In this review, we perform a thorough analysis of the scope and limitations on the different reaction variants with their starting materials, the three-dimensional solid-state conformations of the Asinger derivatives, and we underline and classify all the major post-modifications that have been described. In addition, we report all the major applications in drug discovery projects.

Three-component reaction toward polyannulated quinazolinones, benzoxazinones, and benzothiazinones

An efficient conversion of readily accessible cyclic imines with acid chlorides, that are able to take part in nucleophilic aromatic substitution (SNAr) reactions is realized in a new three-component, one-pot reaction, giving at least tricyclic annulated quinazolinones, benzoxazinones, and benzothiazinones as a result of the employed nitrogen, oxygen, or sulfur nucleophiles, respectively. Especially in the case of quinazolinones, this convenient strategy enables the access to heterocycles of heightened diversity, which offer the development of efficient derivatizations of the elaborated heterocyclic scaffolds. In a subsequent Heck or Ullmann cyclization, further annulations to the mentioned quinazolinones can be carried out.

A new multicomponent reaction: unexpected formation of derivatizable cyclic α-alkoxy isothioureas

With the aid of an unexpected new multicomponent reaction 2,5-dihydro-1,3-thiazole S-monoxides can be converted to cyclic α-alkoxy isothioureas. In addition, an observed rearrangement of subsequently acylated isothioureas is described.